Energymaterials, science at HZBblogBlog Helmholtz-Zentrum Berlin2018-05-22T11:36:25Zhttp://energymaterials.hzbblog.de/feed/atomWordPressSilvia Zerbehttp://energymaterials.hzbblog.de/?p=7222018-05-22T11:36:25Z2018-05-22T11:36:25ZIt was after a telephone call in 2003 that Manuela Klaus’s career took off. Right about the time Klaus had just graduated in materials sciences from TU Berlin, the phone rang in the office of Christoph Genzel of the Microstructure and Residual Stress Analysis department. “It was a drill bit manufacturing company from Baden-Württemberg calling,” the department head recollects. The callers needed help with improving their drill bits: they wanted to measure the residual stress of the material at the precise points where the bits are most stressed – “and I said there are no methods to do that yet. But I know of justRead More →

It was after a telephone call in 2003 that Manuela Klaus’s career took off. Right about the time Klaus had just graduated in materials sciences from TU Berlin, the phone rang in the office of Christoph Genzel of the Microstructure and Residual Stress Analysis department. “It was a drill bit manufacturing company from Baden-Württemberg calling,” the department head recollects. The callers needed help with improving their drill bits: they wanted to measure the residual stress of the material at the precise points where the bits are most stressed – “and I said there are no methods to do that yet. But I know of just the budding doctoral student who could develop one.”

So the deal was made. Manuela Klaus received a PhD position that was entirely funded by the Baden-Württemberg company – and in return the company received experimental data of a precision unprecedented for this specific problem. “I studied hundreds of samples for that,” Manuela Klaus says, looking back at her doctoral phase. It was to be the prelude to the research she is still pursuing today. Using synchrotron radiation from BESSY II and neutrons from the research reactor BER II, the 39-year-old researcher and her colleagues are studying the product characteristics of various materials and developing ever new methods and approaches to achieving the most accurate results possible – and to perform experiments that have never been technically feasible before.

Team spirit is important

Manuela Klaus sits in a conference room at the research centre in Adlershof, her long dark hair bound together into a ponytail. The team meeting has just finished. The colleagues from Adlershof and Wannsee have caught up on the usual matters they discuss at their ten o’clock Wednesday get-togethers: current projects, recent developments and new results. “We work closely together,” Manuela Klaus says after the meeting. Team spirit is important to her; one senses that immediately. On the table before her is a box she has placed there, still closed. Beside it is a model depicting how atoms are arranged inside a material. It is built in a cube shape out of many little balls joined together with thin rods. “Now, if I squeeze the material here,” she says, pushing her hand down onto the cube from above, “then the atoms are pressed closer together, while the material bulges out the sides.” She uses this model often when she needs to explain the subject of her research: residual stress. At this point, the department head Christoph Genzel happens to be walking by. He chips in: “Imagine an empty beer bottle. You can use it to hammer a nail into the wall; that’s how hard it is. But if you drop the nail in through the neck, it will smash out the base of the bottle. That’s residual stress.”

Clients: Car makers and suppliers and aerospace companies

Residual stress is not just an academic concept, and hardly anyone knows this better than Mirko Boin. Manuela Klaus goes to fetch him from his office next door. Boin, who has a doctorate in materials science, is the industrial contact for the team. He opens the cardboard box on the conference table and takes out about a dozen metal parts. “These are projects we last worked on,” he explains. Part of a shaft from a car engine is in there, plus a cylinder head, and the tip of a drill bit. Car makers and suppliers, aerospace companies and enterprises from all kinds of industries who are looking for innovations come to Mirko Boin. Residual stress is often used as an indicator of the quality of a product. In elaborate experiments, attempts are made to harden materials so that highly stressed parts, in engines for example, can continue to function reliably over decades. “This here for example,” says Christoph Genzel, taking a thumb-sized tappet out of the box, “is a part from the auto industry; a ceramic material.” He picks up the tappet and drops it onto the floor. We hear a metallic-sounding clank, and see a grin on Genzel’s face, who knows most observers would have expected it to be in shards by now. He picks up the unscathed tappet again: “It’s been hardened to have a high residual compressive stress on the outside,” he says – and knows he could drop it several more times without anything breaking.

Additive manufacture is a hot topic in industry

“We are something like the general practitioners people come to with their ailments,” those in the Microstructure and Residual Stress Analysis department cheekily put it – and the fact is, there are plenty of patients. Sometimes they will be developing a new steel whose properties have to be precisely measured, and most recently there has been a lot of demand in so-called additive manufacture – a type of 3D printing out of metal – in which many industries are placing a lot of hope. “On average, we probably get one enquiry from industry a week,” Mirko Boin says. Sometimes, the customer needs one specific part to be tested (and soon, please); sometimes they will have more like 50 samples to be studied. And in so many cases, there are no existing testing methods for the specific task – much like the time when Manuela Klaus did her thesis. “All the tests we perform in our department are done on samples from customers, because we don’t make any parts ourselves,” Manuela Klaus says. By now, we have walked from the conference room to her team’s experimental station, which is called EDDI (Energy Dispersive Diffraction). Painted a striking shade of blue, it practically leaps out at the eye in the experimental hall of BESSY II. She is normally here two days a week, performing her experiments. The rest of the time she spends in her office, preparing for the next measurements and processing the data for the new experiments. “With some companies who come to us, the experts have a pretty good idea of what we do here,” says Manuela Klaus, “but we also get those who are only hearing about residual stress for the first time, from us.”

“The Partnership with industry goes hand-in-hand for us.”

What she and her team do is an example of how partnership with industry can also enrich research – “because that goes hand-in-hand for us,” as she puts it. All the time, they receive requests that involve a great deal of research before any testing can happen. But a lot of this research also results in articles in prestigious science journals. As one example, large-scale motor parts need to be tested at very specific points in order to determine their properties. “You can only really reach the test points if you saw the whole thing up, but then the material’s properties change,” the team knows all too well – and that is where their creativity comes in.

Right now, Manuela Klaus and her colleagues are feeling the winds of change: They can only continue working in the experimental cabin at BESSY II until next summer. So, two new pieces of laboratory equipment are currently being set up in Adlershof and Wannsee, based on new technology: these so-called MetalJet high flow X-ray sources will deliver hard X-ray light at a similar quality to that of BESSY II.

“But, of course, they’re already working on their next innovation.”

But there is one thing that will never change, and that is the number of enquiries for cooperation from industry. “In the beginning, we thought: once we have tested the new material, we won’t ever hear from that company again, because they will have got their results,” Manuela Klaus says with a smirk. “But, of course, they’re already working on their next innovation, and so it continues.” Even now, there is a new drill bit lying on her desk from the same Baden-Württemberg company for whom she developed the testing method for her doctorate – their cooperation has continued the whole time in the one and a half decades since.

]]>0aröhttp://energymaterials.hzbblog.de/?p=7032018-03-23T10:59:01Z2018-03-23T10:36:16ZAt the Interdisciplinary conference on „INNOVATION IN SOLAR BUILDING SKINS & ENERGY EFFICIENCY TOWARDS SUSTAINABLE CITIES”, 19th to 20th march in Berlin, experts from the building sector, politics, finance and photovoltaics discussed why Building Integrated Photovoltaics (BIPV) is not already more widely applied in buildings (see also HZB-webinfo ) and what innovations are still needed. Statements from participants of the conference: Lighthouse projects show what is possible Impressive projects by architects and engineering offices demonstrate what can be done already: Elegant modern buildings with solar facades and solar active materials for windows, pavements or other surfaces do not only provide energy and mitigate climateRead More →

At the Interdisciplinary conference on „INNOVATION IN SOLAR BUILDING SKINS & ENERGY EFFICIENCY TOWARDS SUSTAINABLE CITIES”, 19th to 20th march in Berlin, experts from the building sector, politics, finance and photovoltaics discussed why Building Integrated Photovoltaics (BIPV) is not already more widely applied in buildings (see also HZB-webinfo ) and what innovations are still needed.

Statements from participants of the conference:

Philippe Macé, Bequerel Institute Belgium: “BIPV has been slow to develop but now I am more optimistic since EU regulation such as the Energy Performance of Buildings Directive with NZEB requirements will increase the interest for BIPV solutions. In addition, these solutions are now cheaper thanks to steep cost reductions of PV components, and we see finally some standards being developed for BIPV.”

And Sierra Cobb, architect, COSA points out:” It was interesting to see people from multiple sectors – communications, PV products, architecture, real estate, and politics – discuss the direction of BIPV. We are interested in the latest technological innovations, thus this interdisciplinary dialog is essential.”

Bianca Lim, ISFH: „I was surprised how nearly all speakers stressed the point that now legislative measures are needed. Because BIPV solutions do exist in lighthouse projects but to implement them massively, support is essential.”Susanne Rexroth, HTW Berlin: „We need to know more precisely how cost evaluations are done and which costs will be added for maintenance in the future. At my university we are starting now a research project on BIPV, and here I got an overview on the state of the art.”

Lighthouse projects show what is possible

Impressive projects by architects and engineering offices demonstrate what can be done already: Elegant modern buildings with solar facades and solar active materials for windows, pavements or other surfaces do not only provide energy and mitigate climate change, but bring also great living comfort. One example is the Efficiency House Plus in Berlin.

Solutions are there

A wide range of products is already available on the market: Colorful glasses with different degrees of transparency allow architects to choose according to aesthetic requirements. But still, the implementation of Building integrated Photovoltaics (BIPV) on a massive scale is very slow.

Barriers and Drivers for BIPV

Among the barriers for massive implementation of BIPV are low oil and gas prices, real estate speculation but most importantly slow adaption of legislation, mentioned by Claude Turmes, member of the European Parliament. “Germany fails to comply with EU legislation on Near Zero Emission Buildings”, Turmes warned and stressed the necessity to mitigate climate change. But there are also potential drivers: further sinking costs for PV components, rising corporate social responsibility and the awareness that modern solutions could add more than just energy, e.g. comfort, air quality and design.

Offering solutions for different needs

Architect Hille Bekic, Architektenkammer Berlin, stressed the point that solutions are needed not only for new buildings and big investors but as well for older buildings and for private house owners.

Just start now

And Carolien Gehrels, Arcadis, a former vice mayor of Amsterdam said: “Having been a politician, my advice is: don’t expect politicians to have more courage than their voters.”

]]>aröhttp://energymaterials.hzbblog.de/?p=6962018-02-22T07:30:13Z2018-02-22T07:30:13ZEven if quantum physics is well established since roughly ninety years, there are still some quantum effects in matter which have been theoretically predicted but up to now not yet seen experimentally. It was the physicist Hans Bethe, who first described theoretically in 1931 what happens in a one dimensional quantum spin system: under certain conditions, magnetic excitations may interact and give rise to a collective excitation, known as “Bethe strings”. But in real matter, strictly one dimensional systems are rare, so Bethe strings have not been a common phenomenon. Now those Bethe strings have been discovered for the first time experimentally by the AugsburgRead More →

Even if quantum physics is well established since roughly ninety years, there are still some quantum effects in matter which have been theoretically predicted but up to now not yet seen experimentally. It was the physicist Hans Bethe, who first described theoretically in 1931 what happens in a one dimensional quantum spin system: under certain conditions, magnetic excitations may interact and give rise to a collective excitation, known as “Bethe strings”. But in real matter, strictly one dimensional systems are rare, so Bethe strings have not been a common phenomenon.

Now those Bethe strings have been discovered for the first time experimentally by the Augsburg physicists Prof. Dr. Alois Loidl and Dr. Zhe Wang and partners from Berlin, Dresden, Mumbai, Nijmegen and San Diego. The scientists did experiments on samples provided by the HZB team of Prof. Dr. Bella Lake, who also looks for hidden quantum effects in matter.

One of the large SrCo₂V₂O₈ crystals, produced in the zone melting furnace at HZB.

The samples consisted of SrCo₂V₂O₈ crystals, in which the cobalt ions form a one-dimensional spin chain. This spin chain features anisotropic magnetic interactions and is known as antiferromagnetic Heisenberg-Ising chain. The crystals, which are unusually big and of excellent quality, were obtained from powder samples with the help of a zone melting furnace at HZB (shown in the upper picture). With extremely high magnetic fields up to 28 Tesla, at the High Field Magnet Laboratory in Nijmegen, the collective excitation could be achieved and further experiments could prove their nature as Bethe strings. The international team has published these results in “Nature”. Even if no immediate application is on the horizon, it is a step forward in understanding matter on a deeper level.

]]>aröhttp://energymaterials.hzbblog.de/?p=6882018-02-01T14:47:40Z2018-02-01T14:43:26ZAn unusual science conference (not only) for young female scientists: April 29-30, 2018 Near the city of Goslar in the beautiful Harz mountains, an unusual science meeting is organised. The location is the Mönchehaus Museum (www.moenchehaus.de). I was attending this conference some years ago and I can really recommend it. The speakers are exclusively very renowned women in materials science, heading institutes at MIT, MPG or other prestigious research institutions. And multiple occasions are given to get into exchange with them. Discussions were open and vivid, and I guess many young women got motivated to strive for a scientific career. The organiser, Prof Katarina Al-Shamery, CarlRead More →

An unusual science conference (not only) for young female scientists: April 29-30, 2018

Near the city of Goslar in the beautiful Harz mountains, an unusual science meeting is organised. The location is the Mönchehaus Museum (www.moenchehaus.de). I was attending this conference some years ago and I can really recommend it. The speakers are exclusively very renowned women in materials science, heading institutes at MIT, MPG or other prestigious research institutions. And multiple occasions are given to get into exchange with them. Discussions were open and vivid, and I guess many young women got motivated to strive for a scientific career.

The organiser, Prof Katarina Al-Shamery, Carl von Ossietzky University Oldenburg, invites young scientists to apply and present a poster. Also male young scientists are welcome.

The scientific meeting takes place April 29 and 30, 2018.

Deadline for registration and contributions is April 1, 2018.

The meeting is held by the Graduate Research School 2226 “Chemical Bond Activation” (Oldenburg) and further supported by the SFB 1083 “Structure and Dynamics of Internal Interfaces” (Marburg).

]]>RShttp://energymaterials.hzbblog.de/?p=6712018-01-22T15:12:42Z2018-01-22T15:12:42ZThe first polish synchrotron radiation facility is brandnew. It was started in 2015, and the center is striving to serve first users at two beamlines starting in early summer 2018. So I was prepared for seeing a fancy new machine, and entering the scene on a bright november(1) morning I found SOLARIS doing its name credit. Model railways for grown ups To me the workshop resembled a meeting of specialists of electric toy railways. The waggons are the electron bunches, and the beam runs on the rail route, round and round. And, if it needs to get “pimped up” after a while, whom to betterRead More →

The first polish synchrotron radiation facility is brandnew. It was started in 2015, and the center is striving to serve first users at two beamlines starting in early summer 2018. So I was prepared for seeing a fancy new machine, and entering the scene on a bright november(1) morning I found SOLARIS doing its name credit.

Entrance of SOLARIS. Credit: RS

Model railways for grown ups

To me the workshop resembled a meeting of specialists of electric toy railways. The waggons are the electron bunches, and the beam runs on the rail route, round and round. And, if it needs to get “pimped up” after a while, whom to better ask than others who run another electric railway, too? Looking at it that way it´s clear that a sightseeing tour through SOLARIS in the end was a “must”!

Some facts about SOLARIS:

The synchrotron is built following the scheme: Gun-LINAC-storage ring, with four power RF-units, which feed six LINAC sections, and that so far lies underground.

RS

The accelerating machine and storage ring is positioned eight metres higher, on (the above) ground level, and the distance between the deeper tunnel and the ground floor is bridged by a “transfer line”.

SOLARIS works with normal conducting cavities. Two cavities power the acceleration, and two more cavities are needed for beam geometry.

SOLARIS Cavities. Credit: RS

The beam travels through 12 double bend achromat cells, each of them weighing six tons. The total energy is 1,5 GeV, and the light serves two beamlines (up to date). SOLARIS is built the way like the MAX IV facility in Lund.

To me all I saw seemed a very solid facility, ready to run and soon to come. And hence it´s still so new, everything is so exactly placed and tidied up, nice, nice, nice.

SOLARIS, experimental Hall. Credit. RS

This together with our friendly RF hosts from the synchrotron plus the romantic old town of Kraków, well, I must say, I enjoyed the visit more than much.

What drives my curiosity on accelerator physics?

And somewhere on this trip I finally found my answer to why all this weird accelerator tourism motivation. When I was small I asked for an electric toy railway – and got none. “You´re a girl”, was the explanation. Hm. Now I´m a grown up girl – and gained access to some of the most thrilling and fascinating ones in the world.

(Footnote 1): On the workshop

My visit took place during the 2017 ESLS-RF (European Synchrotron Light Sources Radio Frequency) workshop mid of november which was hosted by the polish synchrotron SOLARIS http://www.synchrotron.uj.edu.pl/ in Kraków.

And the topic of this “ESLS-RF” workshop? At first, we were given reports from RF colleagues from all over Europe and their labs. Presentations were followed by lively discussions, such as, what experiences since the last workshop with what materials led to what results. One of the favourite topics in these RF discussions are always different types and latest experiences with “Solid State Amplifiers”, of course. And we all got to know the current status of the “machines” like Diamond (UK), Elettra (Italy), ALBA (Spain), MAX IV (Sweden), ESLS and SOLEIL (France), DESY, KIT, DELTA (Germany) and many more.

]]>Beatrix Seidlhoferhttp://energymaterials.hzbblog.de/?p=6472018-01-11T15:23:18Z2018-01-11T10:36:00Z Romania joined the European Union in 2007, continuing to be one of the poorest of its member states – for comparison, Germany’s GDP is currently €38 000 whereas Romania’s is instead €8 600. However through education and research a way to a better future can be paved. It was for this reason that we went on the road in October 2017. We wanted to tell our Romanian colleagues about the different possibilities that European light sources offer to their research, and about which funding possibilities they could apply for. Hardly any of them were aware that the use of the facilities is free ofRead More →

Romania joined the European Union in 2007, continuing to be one of the poorest of its member states – for comparison, Germany’s GDP is currently €38 000 whereas Romania’s is instead €8 600. However through education and research a way to a better future can be paved. It was for this reason that we went on the road in October 2017. We wanted to tell our Romanian colleagues about the different possibilities that European light sources offer to their research, and about which funding possibilities they could apply for. Hardly any of them were aware that the use of the facilities is free of charge for University researchers, nor did they know that two of the users could also receive financial support for the measurement time.

CALIPSOplus and the Twinning Programme

My boss, Antje Vollmer, who leads the User Coordination office here at HZB, presented the European light source landscape, CALIPSOplus and the Twinning Programme at several Romanian Universities. After the presentation, we had the opportunity to visit different Departments and to have small chats with the scientists about their research and their specific needs for the partnering programme.

Dr. Antje Vollmer outlines the financial support offered through CALIPSOplus and the Twinning Programme. Photo: B.Seidlhofer

In general, the information was received with enthusiasm and great interest. Some colleagues from Romania were even already prepared to submit a beamtime proposal while in parallel participating in the Twinning Programme – a programme in which a guest user is partnered with an experienced group and enjoys a hands-on introduction to synchrotron-based experiments. The research they presented in Romania is very up-to-date and innovative, and all scientific insights were shared with great enthusiasm. There were several groups involved in Solar Cell research, but we also learned about interesting projects in Microbiology, Magnetism and Bionics.

Curious graduation students

In Timisoara I had my own presentation to last year high school students at the request of Professor Daniel Vizman. I wouldn’t have imagined myself that such young students could be interested in these subjects. My lecture was aimed at attracting new students to Physics, and particularly to the University of Timisoara. Why? All the colleagues we spoke to in Romania had the same complaint: there are fewer and fewer graduates choosing to study Physics or Chemistry. Other fields, such as Computer Science or Economics, are more attractive offering a better financial future. Unfortunately, this leads to fewer people to drive Romanian research further.

I held my lecture in Romanian. I was brought up in Romania as a young child, so my Romanian language skills are good enough to have proper conversations. Some technical words and expressions were however a bit tough. That ended up to my advantage, because I was then able to engage the students who were very eager to lend a hand and correct me whenever necessary. Since they also spoke very good English – movies, tv shows and many books in Romania are routinely available in English – they could help me promptly without any communication issues.

At the end of my presentation, the young students were very inquisitive and interested. I told them many details about our light source and what we can investigate with it, but also which job prospects exist in science. One student was especially interested in Patents and how they work. As you can see, money plays an important role even for such young people. My boss Antje told me later that I received a “standing ovation”. In the end, I think the lecture was indeed very much worth it for the students, even if only for the many questions addressed in the end.

Indispensable: Personal contact

This first visit as part of the CALIPSOplus Partner Program showed us how important it is to personally contact colleagues from all over Europe and to discuss possible cooperation and EU-wide opportunities. In countries like Romania, but also in other new EU member states (EU13 countries), there are many talented people, who are full of ideas and who develop sophisticated measurement setups even with the little money they have! It is indeed a pity that there are few opportunities to finance them. Here in Germany I was lucky, I was paid during my doctoral thesis – in other countries it is not always the case. Of course, young people are then often directed toward more financially rewarding careers.

And now the hard facts:

At the very end, the important hard facts: The EU-funded CALIPSOplus project supports international exchanges of researchers and transnational access to European light sources. In particular, the program is aimed at scientifically integrating EU13 countries, which have so far not been taking advantage of the excellent light sources available in the European territory.

]]>aröhttp://energymaterials.hzbblog.de/?p=6292017-12-21T14:29:51Z2017-12-21T14:29:31ZNanoparticles are tiny, really tiny. Only a fraction of a micrometer or some nanometers in size. And only some thousands of molecules strong, their properties can differ dramatically from those of their larger cousins. Titaniumdioxide, a whitish powder, can form such nanoparticles. In water, these nanoparticles can act as catalysts, when excited with light. and facilitate water splitting or water remediation. However, what happens exactly when TiO2 and water get into contact and which impact this is having on the electronic structure of TiO2 remained in the dark: it is very tricky to probe nanoparticle–water interface experimentally and to observe changes. Soft X-rays at BESSYRead More →

Nanoparticles are tiny, really tiny. Only a fraction of a micrometer or some nanometers in size. And only some thousands of molecules strong, their properties can differ dramatically from those of their larger cousins. Titaniumdioxide, a whitish powder, can form such nanoparticles. In water, these nanoparticles can act as catalysts, when excited with light. and facilitate water splitting or water remediation.

However, what happens exactly when TiO2 and water get into contact and which impact this is having on the electronic structure of TiO2 remained in the dark: it is very tricky to probe nanoparticle–water interface experimentally and to observe changes.

Soft X-rays at BESSY II

One method is available at BESSY II: It is Soft X-ray absorption spectroscopy, which has already been used to characterize the electronic structure of TiO2 materials, but so far only in vacuum conditions.

Now, Freigeist-fellow Tristan Petit and his team could present a first study of TiO2 nanoparticles measured directly in aqueous dispersion. For this purpose, they developed a new method to probe nanomaterials in liquid using a holey membrane-based flow cell. With this approach, the X-ray transmission of the membrane was increased, especially in the water window, compared to solid membranes.

Sketch of the holey membrane flow cell/ T. Petit.

In their summary, they point out how Ti-O bonds can be distorted by interaction with water molecules. “These interactions may stabilize the smallest TiO2 nanoparticles, which have an electronic signature similar to amorphous films when dried in vacuum,” the scientists conclude.

An artist’s view of the holey flow cell was displayed on the cover of Adv. Mat. Interfaces. Credit: T. Splettstoesser/scistyle.com

More information:

The study was published in Advanced Materials Interfaces, (23/2017), december 2017. “Colloidal Systems: X-Ray Absorption Spectroscopy of TiO2 Nanoparticles in Water Using a Holey Membrane-Based Flow Cell”

]]>aröhttp://energymaterials.hzbblog.de/?p=6122017-12-15T09:13:46Z2017-12-14T13:50:55ZAltmetrics just published the list of the top 100 scientific articles of 2017, which attracted the most online attention. None of the articles in the top 100 is dealing with materials research. Nevertheless, already the second most spread article is concerning us as well: It is a study on mental health of PhD students. The paper was spread more than 7000 times by twitter, posted 117 times on facebook and quoted in more than 20 online-articles. And it is giving food for thought: Every third PhD suffering seriously According to the study “Work organization and mental health problems in PhD students”, published in Research Policy,Read More →

Altmetrics just published the list of the top 100 scientific articles of 2017, which attracted the most online attention. None of the articles in the top 100 is dealing with materials research. Nevertheless, already the second most spread article is concerning us as well: It is a study on mental health of PhD students. The paper was spread more than 7000 times by twitter, posted 117 times on facebook and quoted in more than 20 online-articles. And it is giving food for thought:

Results based on big sample

The authors assessed the mental health of a representative sample of 3659 PhD students in Flanders, Belgium and compared them to other groups of highly educated professionals inside and outside of academia. The mental health problems were approximately twice as prevalent in the PhD population than in other groups of highly educated people.

Work-life balance impaired

In their conclusion the authors point out that students feel often not able to maintain a healthy work-life balance due to high expectations and workloads. The supervisor’s leadership style and the team decision-making culture can have big impacts on student’s well being and feeling of control. Also awareness of career options outside academia might help relieving pressure.

Good leadership style and team spirit can reduce unnecessary strain.

Recommendations:

The authors write in their conclusion:

“..Our analyses suggest that universities will benefit in terms of PhD students’ mental health when they facilitate management of work-family balance and workload, design open decision-making procedures, and help PhD supervisors to adopt leadership styles that lead to satisfactory and constructive work relations. Our findings also suggest that universities might benefit from offering PhD students clear and full information on job expectations and career prospects, both in and outside academia.”

Footnote: Altmetrics is counting mentions in diverse social media, from twitter, blogs, Facebook, reddit, google+, videos or newsstories online. Among the Altmetrics top 100 in 2017, are mostly research papers on health and life sciences. The top mentioned paper debunks the myth that fat is always bad for health.

]]>aröhttp://energymaterials.hzbblog.de/?p=6032017-12-11T15:23:17Z2017-12-11T15:23:17ZAn international team of scientists has greatly improved the stability of organic-inorganic lead halide perovskites. These materials have enormous potential for photovoltaic applications, but still suffer from relatively short device lifetimes. Guanidinium replaces some traditional cations The scientists, led by researchers from the EPFL in Lausanne, Switzerland, incorporated a large organic cation – guanidinium – into the perovskite crystal structure, partly replacing the methylammonium and formamidinium cations used traditionally. Conversion efficiency 19 % Overall, the new material delivered average power conversion efficiencies of over 19%, and increased operation to 1,000 h under continuous illumination. This is an important step for research in the perovskite field. ScientistsRead More →

An international team of scientists has greatly improved the stability of organic-inorganic lead halide perovskites. These materials have enormous potential for photovoltaic applications, but still suffer from relatively short device lifetimes.

Guanidinium replaces some traditional cations

The scientists, led by researchers from the EPFL in Lausanne, Switzerland, incorporated a large organic cation – guanidinium – into the perovskite crystal structure, partly replacing the methylammonium and formamidinium cations used traditionally.

Conversion efficiency 19 %

Overall, the new material delivered average power conversion efficiencies of over 19%, and increased operation to 1,000 h under continuous illumination. This is an important step for research in the perovskite field.

Scientists at HZB and HU

Two of the authors, Norbert Koch and Maryline Ralaiarisoa, are members of the Molecular Systems research group. This is a collaboration between the Helmholtz-Zentrum Berlin and the Humboldt-Universität zu Berlin. Maryline is working on her PhD and is enrolled in the HZB-HU hybrid4energy Graduate School.

Their results have been published in Nature Energy: Large guanidinium cation mixed with methylammonium in lead iodide perovskites for 19% efficient solar cells

PS: The picture shown above this text is not given in the mentioned paper, but taken from Wikipedia, CC BY 4.0. It illustrates the “classical” organic-inorganic perovskite: A Methylammonium cation (CH3NH3+) is surrounded by 12 nearest-neighbour iodide ions in corner-sharing PbI6 octahedra. Credit: By Christopher Eames et al. – http://www.nature.com/ncomms/2015/150624/ncomms8497/full/ncomms8497.html, CC BY 4.0

]]>Silvia Zerbehttp://energymaterials.hzbblog.de/?p=5822017-12-04T12:51:50Z2017-12-04T10:25:11ZAt HZB we often have interesting guests from abroad – and with challenging topics. I met two of them, Vitaly Datsyuk and Svitlana Trotsenko, on a sunny autumn day. The first time Vitaly and Svitlana came to HZB in Wannsee, they were stopped at the gate. Both scientists work in the Physics Department of Freie Universität Berlin on a Ukrainian passport. But because the requisite application as required by the Foreign Trade and Payments Act hadn’t gone through, the two had to leave empty handed. And yet, this minor hiccup did not stop them from returning. In fact now, once a month, they are regularRead More →

At HZB we often have interesting guests from abroad – and with challenging topics. I met two of them, Vitaly Datsyuk and Svitlana Trotsenko, on a sunny autumn day.

The first time Vitaly and Svitlana came to HZB in Wannsee, they were stopped at the gate. Both scientists work in the Physics Department of Freie Universität Berlin on a Ukrainian passport. But because the requisite application as required by the Foreign Trade and Payments Act hadn’t gone through, the two had to leave empty handed. And yet, this minor hiccup did not stop them from returning. In fact now, once a month, they are regular guests at the HZB CoreLab “Correlative Microscopy and Spectroscopy”.

Here, researchers can use the latest scanning electron and ion microscopes developed by ZEISS to produce nanoscale images of their materials. “The microscopy lab at HZB is the most important partner for us because only here do we find the suitable methods for studying our samples,” says Svitlana Trotsenko. The researchers used the helium ion microscope. This is a prototype from ZEISS, and one of the few in the world that the company has built so far.

Wanted: Materials that insulate heat

The two FU researchers are developing materials that are especially good at insulating heat. Such materials are in demand as facade insulation, for example. “The project is being funded by the Federal Ministry of Research and is of great economic interest. So, we are working very closely together with industrial partners,” Vitaly Datsyuk explains.

To reduce the thermal conductivity of such materials further – so that they insulate even better – the FU researchers are using electrospinning technology. They develop a new class of the nanofiber –based insulation materials which are easy to use and suitable for new construction as well as renovation of older buildings to improve energy using. Additionally they try to solve a problem with recycling polystyrene from waste materials. “Our technology is low cost, since it is based on renewable and waste sources”. With the help of the helium ion microscope, the researchers can reveal detailed images of the sample’s surface structure and determine what influence the porous nanostructures have on the thermal conductivity of the material.

Only at HZB: a prototype of ZEISS helium ion microscope

“The helium ion microscope is ideal because our samples consist of nonconductive materials, which cannot be studied with conventional ion microscopes,” Svitlana Trotsenko explains. So they are greatly pleased to be cooperating with HZB, and especially with such helpful supervision. “Katja Höflich is a very dedicated and far-sighted expert. When we discuss our experimental results together, it brings us an incredibly long way forward,” says Vitaly Datsyuk.

]]>aröhttp://energymaterials.hzbblog.de/?p=5682017-11-24T15:08:46Z2017-11-24T15:08:46ZSource: SESAME Thursday, November 23, 2017: At 10:50 yesterday morning scientists at the pioneering SESAME light source saw First Monochromatic Light through the XAFS/XRF spectroscopy beamline. This signals the start of the laboratory’s experimental programme. The beamline delivers X-ray light that will be used to carry out research in areas ranging from solid state physics to environmental science and archaeology. “After years of preparation, it’s great to see light on target,” said beamline scientist Messaoud Harfouche. “We have a fantastic experimental programme ahead of us, starting with an experiment to investigate heavy metals contaminating soils in the region.” Two beamlines for a start, a third one inRead More →

At 10:50 yesterday morning scientists at the pioneering SESAME light source saw First Monochromatic Light through the XAFS/XRF spectroscopy beamline. This signals the start of the laboratory’s experimental programme. The beamline delivers X-ray light that will be used to carry out research in areas ranging from solid state physics to environmental science and archaeology.

“After years of preparation, it’s great to see light on target,” said beamline scientist Messaoud Harfouche. “We have a fantastic experimental programme ahead of us, starting with an experiment to investigate heavy metals contaminating soils in the region.”

Two beamlines for a start, a third one in 2018

The initial research programme will be carried out at two beamlines, the XAFS/XRF beamline and the Infrared (IR) spectromicroscopy beamline that is scheduled to join the XAFS/XRF beamline this year. A third beamline, devoted to materials science, will come on stream in 2018.

“Our first three beamlines already give SESAME a wide range of research options to fulfil the needs of our research community,” said SESAME Scientific Director Giorgio Paolucci. “The future for light source research in the Middle East and neighbouring countries is looking very bright!”

Next steps of commissioning

First Light is an important step in the commissioning process of a new synchrotron light source, but it is nevertheless just one step on the way to full operation. The SESAME synchrotron is currently operating with a beam current of just over 80 milliamps, while the design value is 400 milliamps. Over the coming months as experiments get underway, the current will be gradually increased.

Science and Peace

“SESAME is a major scientific and technological addition to research and education in the Middle East and beyond,” said Director of SESAME, Khaled Toukan. “Jordan supported the project financially and politically since its inception in 2004 for the benefit of science and peace in the region. The young scientists, physicists, engineers and administrators who have built SESAME, come for the first time from this part of the world.”

Improving life, exploring culture

Among the subjects likely to be studied in early experiments are environmental pollution with a view to improving public health, as well as studies aimed at identifying new drugs for cancer therapy, and cultural heritage studies ranging from bioarcheology – the study of our ancestors – to investigations of ancient manuscripts.

“On behalf of the SESAME Council, I’d like to congratulate the SESAME staff on this wonderful milestone,” said President of the Council, Rolf Heuer. “SESAME is a great addition to the region’s research infrastructure, allowing scientists from the region access to the kind of facility that they previously had to travel to Europe or the US to use.”

]]>Fabian Weberhttp://energymaterials.hzbblog.de/?p=5552017-11-09T10:12:20Z2017-11-06T23:15:44ZAs a doctoral researcher of the Helmholtz-Zentrum Berlin, I enjoy a lot of freedom to structure my research as I want to – especially, since we are usually not part of giving lectures or tutorials like the doctoral researchers at universities. By partaking in the summer student program, I learned though that teaching someone else can teach you a lot yourself. Taking the decision Only a few months after having started my doctoral research, we had a first summer student in our workgroup. At that time, I was very impressed by the sheer amount of work that this summer student could provide and thus sawRead More →

As a doctoral researcher of the Helmholtz-Zentrum Berlin, I enjoy a lot of freedom to structure my research as I want to – especially, since we are usually not part of giving lectures or tutorials like the doctoral researchers at universities. By partaking in the summer student program, I learned though that teaching someone else can teach you a lot yourself.

Taking the decision

Only a few months after having started my doctoral research, we had a first summer student in our workgroup. At that time, I was very impressed by the sheer amount of work that this summer student could provide and thus saw a clear benefit from the program for my own project. Also, it was exciting to meet someone from abroad and getting to know each other. Hence, I decided on applying for the next program myself.

Making plans

With this decision, however, came also the duty of planning a work program that was doable for a student in his/her 5th to 6th semester. So I sat down, and revisited how far I was with my own research and what I wanted to still achieve within my thesis; which is something that is advised to every doctoral researcher over and over, anyway. However, I then had to decide what portion of my PhD project I could distribute – and whether it was research that would yield meaningful results within the two months of the summer student program.

Of course, I also wanted to plan out the project as „robust“ as possible – such that nothing could go wrong for the student. Thinking about that now, despite being a bit tedious, the plan-making in itself was already an exciting experience, since I was practically going to have a Mini-workgroup of my own for a short period. I also felt a huge responsibility – since this person would more or less fully trust a plan that I „just made up“.

Kindling the fire of interest

While preparing the topic, I sometimes wondered about what I would do, in case the summer student did not want to work on the proposed topic. At this thought, I recalled a famous quote that I learned in a rhethoric course once:

„You cannot kindle a fire in any other heart until it is burning in your own.“ (Ralph Waldo Emerson)

Since I had been preparing the whole workplan for my summer student for weeks already, I was pretty excited myself to see what we could achieve within the project. So, when she finally arrived I took most my own worktime during the first week for explaining the first tasks personally – since I knew that the more she understood what we were trying to do, the more self-governed she could work and learn. Also I remembered from my own internships that I always felt rewarded, once I was able to do a difficult task completely on my own.

Tending the spark

Then, each time she finished some major step of the project, we would discuss her findings together. Sometimes, when we would hit questionable results, I had to rethink our strategy a little – like I naturally do for my own work as well. However, since it was not me personally who obtained the strange results I actually felt even worse than if I had produced them myself. In the end, she was of course following my lead and could not as critically question each of the tasks like I could have done. So I also learned to plan every next step with even more caution before passing it on to her.

Like this, every time we would start a new type of task, we would then sit down and run quickly through the theory together – also trying to establish links between the tasks, like „why we would need the prior step to do the next“ and so on. After we had finally covered every building block of the project, I then tried to rather provide guidance and counsel than keeping the strict workflow, since I knew from my own experience that passing on a sense of self-responsibility and trust was the last ingredient for conveying a „burning interest“. I was not expecting though, that once lit, this excitement could also develop a momentum of its own.

Handing on the torch

At the end of the program, the students were to present their results to the other participants. In a small competition of self-written abstracts, three of the 21 participants could then win the right to give a ten minute oral presentation on their topic at the last day. And since my student was starting to „burn for her topic“, she wanted to also show the others what she had achieved and to convey the spark of interest even further.

So she spent a lot of time on refining her abstract completely self-governed such that she could win the interest of the others. From time to time, she wanted me to give her abstract a look, but her eagerness for this self-chosen project of her own had started all by itself. Seeing the determination in someone, that I had only known for a couple of weeks for a project that I had designed was an incredible experience that also motivated me for my own work. When she and three of the other summer students finally held their presentations, I was very proud and thankful for her effort.

Conclusion

In conclusion, I was very happy to have been a part of the summer student program, since it was a first possibility for me to learn how to plan out a project, how to motivate others for my own passion and to lead a mini-workgroup for a short time. Although I spent quite some time on this project, we could obtain some nice results together and it was a very rewarding experience to see someone catching fire for my field of interest.

]]>4aröhttp://energymaterials.hzbblog.de/?p=5432017-10-02T16:08:37Z2017-10-02T16:08:37ZLast week 50 scientists from all over the world have gathered at BESSY II. Physicists or chemists, experimentalists or pure theoreticians. It was an interdisciplinary crowd, discussing openly and in an extraordinary friendly way about new and sometimes hypothetical processes in hybrid nanomaterials, how to model them and how to explore and characterizethem experimentally. Freigeist fellow Dr. Annika Bande has invited to this big workshop, sponsored by Volkswagen Foundation. Together with her young team, the theoretical chemist is modelling the dynamics of electrons in semiconductor materials , which upon miniaturization give rise to so called quantum dots. The result: Exchange and new ideas Her goalRead More →

Last week 50 scientists from all over the world have gathered at BESSY II. Physicists or chemists, experimentalists or pure theoreticians. It was an interdisciplinary crowd, discussing openly and in an extraordinary friendly way about new and sometimes hypothetical processes in hybrid nanomaterials, how to model them and how to explore and characterizethem experimentally.

Freigeist fellow Dr. Annika Bande has invited to this big workshop, sponsored by Volkswagen Foundation. Together with her young team, the theoretical chemist is modelling the dynamics of electrons in semiconductor materials , which upon miniaturization give rise to so called quantum dots.

The result: Exchange and new ideas

Her goal is to make predictions which can be tested by experimentalists and thus proceed to their ultimate proof and pave the way towards application. “This workshop was a great occasion to bent one’s mind towards the different backgrounds of contributing scientists and emerge quite unforeseen new research ideas”, she said. Some of the workshop participants might come back soon for more collaboration.

]]>aröhttp://energymaterials.hzbblog.de/?p=5312017-09-27T13:25:38Z2017-09-27T13:14:05ZAll summerstudents will present their projects in a conference at HZB Campus Wannsee on thursday 18 September. The conference will start at 11:00 with four talks. The speakers have been elected by the summerstudents themselves. After lunch, the poster session starts. Every student has prepared a poster presenting her or his project, the context, the motivation and what has been achieved during the two months project in summer 2017. An award is given to the best poster along criteria such as communications skills, layout and design, and – of course – scientific achievement. 11.00-12.00 Oral Presentations 13.30 -15:30 Poster session 16.00 Presentation of the posterRead More →

]]>All summerstudents will present their projects in a conference at HZB Campus Wannsee on thursday 18 September. The conference will start at 11:00 with four talks. The speakers have been elected by the summerstudents themselves. After lunch, the poster session starts. Every student has prepared a poster presenting her or his project, the context, the motivation and what has been achieved during the two months project in summer 2017. An award is given to the best poster along criteria such as communications skills, layout and design, and – of course – scientific achievement.

11.00-12.00 Oral Presentations

13.30 -15:30 Poster session

16.00 Presentation of the poster award and Get-Together in Café Jahn.

All HZB scientists are cordially invited to attend the summerstudents conference.

11.00-12.00 Oral Presentations

Sara Bogojević
“Band gap engineering: how theoretical chemistry can lead to the perfect photocatalyst”

Inês Jordão Pereira
“From plasma plume to solar water splitting”

Konstantin Leškevič
“Invisible processes, significant value”

Norton West
“The next step in cybernetics”

Some of the most beautiful pictures will be (hopefully) presented and explained in the Poster Session.

]]>Piotr Tokarzhttp://energymaterials.hzbblog.de/?p=5052017-09-12T22:47:03Z2017-09-12T08:51:47Z Protein crystals are a tricky matter to study. Sometimes you can get them easily, without any effort, but sometimes to obtain one, you need to work hard and even that doesn’t bring success for a long. Once you get the crystal, it opens the gate to a long process to determine the molecular structure. Crystals are often very delicate and can be easily destroyed by mechanical and chemical agents as well as temperature changes. In view of these obstacles, many applications in macromolecular crystallography would benefit from the availability of a macromolecular crystal system, which exhibits outstanding diffraction properties, which is mechanically stable and radiation-hardRead More →

Protein crystals are a tricky matter to study. Sometimes you can get them easily, without any effort, but sometimes to obtain one, you need to work hard and even that doesn’t bring success for a long.

Once you get the crystal, it opens the gate to a long process to determine the molecular structure. Crystals are often very delicate and can be easily destroyed by mechanical and chemical agents as well as temperature changes.

In view of these obstacles, many applications in macromolecular crystallography would benefit from the availability of a macromolecular crystal system, which exhibits outstanding diffraction properties, which is mechanically stable and radiation-hard and which can be thawed and frozen many times without concomitant loss of diffraction. Due to their large solvent content, macromolecular crystals are typically mechanically rather fragile and little suitable as the basis of such a system.

The method that gives hope to produce such a system is cross-linking using glutaraldehyde, but its use so far was only partially successful due to loss of diffraction properties of a crystal.

Fig.1 A schematic illustration of the cross-linking process

The new approach to glutaraldehyde cross-linking system assumes two steps to achieve stability of macromolecular crystals. Firstly, genetic modification of the protein in order to strengthen existing crystal contacts. The second step then consists of the further stabilization by cross-linking.

In my project, I am trying to perform such a modifications and achieve stable crystals of protein xylanase from the thermophilic fungus Thermoascus aurantiacus.

]]>5Samer Daradkehhttp://energymaterials.hzbblog.de/?p=4922017-09-12T08:03:46Z2017-09-12T07:37:22ZFuel Cell Fuel cell is an energy conversion device that converts the chemical energy stored in fuels (Hydrogen) and oxidants into electricity through electrochemical reaction. We work on specific type of fuel cell which is Polymer electrolyte membrane fuel cell (PEMFC), which is consists of an anode and a cathode, and a polymer electrolyte membrane (PEM) in between. At the anode, hydrogen flows into the flow channel through the gas diffusion layer (GDL) to the catalyst layer (CL). In the anode CL, hydrogen splits into protons (hydrogen ions) and electron, these electron travels through an external circuit to the cathode, thus generate electricity. At theRead More →

Fuel cell is an energy conversion device that converts the chemical energy stored in fuels (Hydrogen) and oxidants into electricity through electrochemical reaction. We work on specific type of fuel cell which is Polymer electrolyte membrane fuel cell (PEMFC), which is consists of an anode and a cathode, and a polymer electrolyte membrane (PEM) in between. At the anode, hydrogen flows into the flow channel through the gas diffusion layer (GDL) to the catalyst layer (CL). In the anode CL, hydrogen splits into protons (hydrogen ions) and electron, these electron travels through an external circuit to the cathode, thus generate electricity. At the same time, on the cathode side, air or oxygen flows through the GDL to CL, where it reacts with the protons and electrons from the anode, producing water and heat.

The production and the distribution of the water inside fuel cell must be investigated because if the amount of water inside the fuel cell is two high that will effect on the performance and the efficiency of the fuel cell, on the other hand, if the amount of water is too low that will cause dehydration the membrane, ohmic resistance of the membrane will increase, the proton transportation in side membrane will decrease, and all of them will effects on the performance and the efficiency of the fuel cell …… so the distribution of water inside the fuel cell must be balanced, so we need the investigate the water distribution inside fuel cell by using neutron imaging.

Neutron imaging

Neutron can be founded in all elements except hydrogen ….. But how we can extract it from the element?

Nuclear reaction: hit the nucleus like U235 with α particle that will generate neutrons, krypton and barium.

Spallation source: hit a suitable nucleus like tungsten (W) or lead (Pd) with high energy proton (1GeV).

Accelerators based source: accelerating a charged particle using electric field which can be generated by van de graaf generator.

How we do the imaging?

The hydrocarbon compound can absorb these neutrons, and that will effect on the intensity of the neutron beam. By using a detector (or sometimes we use CCD camera this will gave us a colored image) place behind the sample (fuel cell) it will record the intensity of the transmitted neutron beam ….. And by using these data (intensity of the incident and transmitted beam and other) we can investigate the amount of water in any specific region in the fuel cell by using imageJ or octopus software.

]]>3Norton Westhttp://energymaterials.hzbblog.de/?p=4672017-09-11T20:49:03Z2017-09-11T20:49:23ZFor a long time, cybernetics was only seen in sci-fi (cyborgs like RoboCop and human enhancements like Inspector Gadget). A current limitation of electric prosthetics, is the human interface. Where the body rejects foreign objects. My project has been investigating a novel self-assembling material nanomaterial, acetylated β3-peptides. These have been demonstrated to assemble into fibers, and when coordinated to metals have been found to metallic like conductivity. As these mimic biological architecture, this material may be biocompatible, and as it forms 2D surface coverage, it’s possible to use it as to transport energy along molecular wires. β3-peptides represent an opportunity for the investigation of aRead More →

]]>For a long time, cybernetics was only seen in sci-fi (cyborgs like RoboCop and human enhancements like Inspector Gadget).

A current limitation of electric prosthetics, is the human interface. Where the body rejects foreign objects. My project has been investigating a novel self-assembling material nanomaterial, acetylated β3-peptides. These have been demonstrated to assemble into fibers, and when coordinated to metals have been found to metallic like conductivity.

As these mimic biological architecture, this material may be biocompatible, and as it forms 2D surface coverage, it’s possible to use it as to transport energy along molecular wires. β3-peptides represent an opportunity for the investigation of a newly discovered nanomaterial which has properties not seen before with potential applications in cutting edge biocompatible energy materials.

Chemical structure of the β3-peptides investigated

This material has been investigated using atomic force microscopy, x-ray photoelectron spectroscopy, and infrared spectroscopy. Specifically, the bonding motif between the peptide and the metal ion.

]]>9Elżbieta Wątorhttp://energymaterials.hzbblog.de/?p=4592017-09-13T11:22:07Z2017-09-11T20:13:37ZProtein crystals are so sensitive, that diffraction experiment conducted in room temperature could easily damage them. Therefore, an important preparation step for diffraction experiment is cooling protein crystals to around 100K. Water is significant part of protein crystals (even to 80%) and it’s a really love-hate relationship. On the one hand, high solvent content provides native environment for protein. Nevertheless, at the same time, during the cooling, water can cause crystals cracking (due to ice formation) or difficulties during diffraction data collection (because of visible ice rings on diffraction pattern). To avoid that, prior to the cooling, the crystals have to be treated using so-called cryo-protectants.Read More →

]]>Protein crystals are so sensitive, that diffraction experiment conducted in room temperature could easily damage them. Therefore, an important preparation step for diffraction experiment is cooling protein crystals to around 100K.

Water is significant part of protein crystals (even to 80%) and it’s a really love-hate relationship. On the one hand, high solvent content provides native environment for protein. Nevertheless, at the same time, during the cooling, water can cause crystals cracking (due to ice formation) or difficulties during diffraction data collection (because of visible ice rings on diffraction pattern). To avoid that, prior to the cooling, the crystals have to be treated using so-called cryo-protectants.

]]>6Konstantin Leskevichttp://energymaterials.hzbblog.de/?p=4582017-09-11T20:50:11Z2017-09-11T20:04:43ZEngineers and scientists all around the world are working together to increase efficiency of photovoltaic (PV) devices. Decreasing manufacturing cost of these devices, together with the cost of produced energy, are making more and more people eager to reduce their carbon footprint. Multiple exciton generating (MEG) solar cells, can produce more energy from single high energy photon by creating multiple electron-hole pairs, these PV’s are more efficient, and have less energy loses due to thermalisation. Unfortunately we still don’t have thorough understanding about MEG processes. MEG solar cell In this project I’ve extend the capabilities of MEG detection system, this was achieved by eliminating manyRead More →

]]>Engineers and scientists all around the world are working together to increase efficiency of photovoltaic (PV) devices. Decreasing manufacturing cost of these devices, together with the cost of produced energy, are making more and more people eager to reduce their carbon footprint.

Multiple exciton generating (MEG) solar cells, can produce more energy from single high energy photon by creating multiple electron-hole pairs, these PV’s are more efficient, and have less energy loses due to thermalisation. Unfortunately we still don’t have thorough understanding about MEG processes.

MEG solar cell

In this project I’ve extend the capabilities of MEG detection system, this was achieved by eliminating many sources of uncertainty, it will allow me to study MEG processes more reliably.

]]>10Jesús Antoniohttp://energymaterials.hzbblog.de/?p=4502017-09-11T19:28:29Z2017-09-11T19:28:29ZOne of the components in a particle accelerator is the photo-injector. In this, the electron beam is generated, accelerated and focused. To achieve the focusing process a solenoid composed of superconducting material connected to a power supply in a certain way is necessary. In the assembly of the photo-injector for the bERLinPro project occurred an error in the connection of the solenoid. Creating an unknown circuit inside of a close system, with high vacuum. This circuit does not allow a process of stabilization of the voltage in not less than 45 min, when desired is less than one minute. In this project is intended toRead More →

One of the components in a particle accelerator is the photo-injector. In this, the electron beam is generated, accelerated and focused. To achieve the focusing process a solenoid composed of superconducting material connected to a power supply in a certain way is necessary. In the assembly of the photo-injector for the bERLinPro project occurred an error in the connection of the solenoid. Creating an unknown circuit inside of a close system, with high vacuum. This circuit does not allow a process of stabilization of the voltage in not less than 45 min, when desired is less than one minute. In this project is intended to create a model circuit that is able to reproduce the measured voltages curves. And using the same model to reduce the time of stabilization.

]]>3Raul Rubiohttp://energymaterials.hzbblog.de/?p=2192017-09-11T18:09:30Z2017-09-11T18:07:19ZOrganic-inorganic hybrid metal-halide perovskites are very interesting materials and can be used as an absorber in photovoltaic device. Efficiencies of solar cells based on metal halide perovskites above 20% have been reported, however, the long-term stability of related solar cells is still challenging. The robustness of triple cation perovskite films seems to indicate the way to obtain a long-term stability. The samples used on the experiments consisted on a substrate with a layer of porphyrin. Their characterization by surface photovoltage (SPV) technique was performed by analyzing its transport length in interaction with the perovskite. The procedure included the measurements before and after the perovskite layerRead More →

]]>Organic-inorganic hybrid metal-halide perovskites are very interesting materials and can be used as an absorber in photovoltaic device. Efficiencies of solar cells based on metal halide perovskites above 20% have been reported, however, the long-term stability of related solar cells is still challenging. The robustness of triple cation perovskite films seems to indicate the way to obtain a long-term stability.

The samples used on the experiments consisted on a substrate with a layer of porphyrin. Their characterization by surface photovoltage (SPV) technique was performed by analyzing its transport length in interaction with the perovskite. The procedure included the measurements before and after the perovskite layer was deposited.

The main idea is to analyze how the responses vary by comparing different thicknesses of porphyrin in contrast with different substrates and find out how are correlated the different parameters.

SPV characterization of the electropolymer based on Zn-porphyrin before (black) and after (red) the perovskite Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 was deposited. The absorbance (thicknesses) of the porphyrin sample in this case was of 0.3.

]]>3Royle Perez Castillohttp://energymaterials.hzbblog.de/?p=3852017-09-11T17:25:32Z2017-09-11T17:23:26ZDue to their unique physical properties and reactivity, metallic nanoparticles (MNPs) play an important role in the design of novel nanodevices, especially in the field of molecular electronics. The optical properties of small MNPs are often determined by the so-called plasmon resonance, which involves the coherent motion of conduction band electrons driven by an external electromagnetic field. In this project, we specifically investigate absorption spectra and electron dynamics upon photoexcitation, for example the difference electron density isosurfaces during excitation by a laser-pulse at the plasmon frequency. Therefore we study the plasmonic response of small, atomistically modeled MNPs using real-time time-dependent density functional theory (RT-TDDFT), asRead More →

]]>Due to their unique physical properties and reactivity, metallic nanoparticles (MNPs) play an important role in the design of novel nanodevices, especially in the field of molecular electronics. The optical properties of small MNPs are often determined by the so-called plasmon resonance, which involves the coherent motion of conduction band electrons driven by an external electromagnetic field.
Na65 difference electron density isosurfaces during excitation by laser-pulse at the plasmon frequency.

In this project, we specifically investigate absorption spectra and electron dynamics upon photoexcitation, for example the difference electron density isosurfaces during excitation by a laser-pulse at the plasmon frequency. Therefore we study the plasmonic response of small, atomistically modeled MNPs using real-time time-dependent density functional theory (RT-TDDFT), as implemented in the OCTOPUS code. Here, we focus on the dependence of the plasmonic frequency on the material and size, comparing Na and Au MNPs. Futher the dependence of the plasmon lifetime is studied with respect to the laser pulse parameters.

]]>2Andrés Felipe Castro Méndezhttp://energymaterials.hzbblog.de/?p=1702017-09-11T17:12:07Z2017-09-11T17:12:07ZTransparent conductive oxides are an important material in the photovoltaic and semiconductor industry. In the past years, Hydrogen doped Indium Oxide (IOH) has shown outstanding electrical and optical properties compared to Aluminum doped Zinc Oxide (AZO). Therefore, it has a high potential as a transparent front contact in CIGS solar cells and modules where this material is commonly used. In this project, we are investigating the properties of pulsed DC-sputtered IOH before and after an annealing on varying substrate layers to successfully implement the material in CIGS. This will help to improve the efficiency of the devices due to a better management of the sunlight. TheRead More →

Transparent conductive oxides are an important material in the photovoltaic and semiconductor industry. In the past years, Hydrogen doped Indium Oxide (IOH) has shown outstanding electrical and optical properties compared to Aluminum doped Zinc Oxide (AZO). Therefore, it has a high potential as a transparent front contact in CIGS solar cells and modules where this material is commonly used. In this project, we are investigating the properties of pulsed DC-sputtered IOH before and after an annealing on varying substrate layers to successfully implement the material in CIGS. This will help to improve the efficiency of the devices due to a better management of the sunlight.